The present invention relates to an electrical connection device between a handle and a steering column in a steering apparatus for a vehicle.
Recently, in connection with a progress of electronic control for an automobile, various kinds of switches have been provided in the handle, which may be called as "a steering wheel", in the steering apparatus for the automobile. Accordingly, there is raised a necessity of connecting these switches with electric cables on the steering column side by means of wiring. Since the handle for the vehicle are constructed so as to rotate in both directions of clockwise and counter-clockwise with several revolutions, a flexible flat cable (FFC) having a plurality of lead wires is generally used in an electrical connection device between the handle and the steering column. In the electrical connection device, the flexible flat cable is arranged between a rotor fixed to a handle axle and a housing fixed to the steering column, in either spiral wound condition or a "reversed" spiral wound condition that the cable is turned up on the half way.
Generally, the electrical connection device includes a cylindrical rotor to which a handle axle of the automobile is fixed and a housing which is fixed to the steering column to rotatably support the rotor at an outside portion thereof. The rotor consists of a first rotor element and a second rotor element to be assembled into the first rotor element from its axial direction. On the other hand, the housing consists of an upper cover and an undercover, both of which define an annular space for accommodating the above-mentioned FFC.
The second rotor element is provided with a flange which extends radially outward of the second rotor element. In assembling the electrical connection device, a cylindrical section of the second rotor element is inserted into a bore of the undercover from its downside and thereafter, the second rotor element is engaged with undercover since the flange of the second rotor element is brought into contact with a bottom surface of the undercover.
In this state, there is only remained a slight clearance between an outer periphery of the cylindrical section of the second rotor element and the an inner edge of the bore of the undercover. Therefore, when the first rotor element rotates together with the second rotor element, the outer periphery of the second rotor element and the inner edge of the bore come into contact with each other, providing sliding surfaces.
In spite of providing the sliding surfaces, the second rotor element and the undercover have been made of resinous materials of relatively large friction coefficient, such as PBT (polybutylene terephthalete), POM (polyoxymethylene) etc. Therefore, in order to reduce the friction coefficient between the sliding surfaces, grease is used thereby to reduce sliding-noise caused by a rotation of the rotor.
However, since this coating operation of grease on the sliding surfaces is complex and wasteful of time, an amount of grease coated is apt to be unequal depending on an operator. Consequently, it is expected that, in case that the amount of grease is too little, the sliding-noise would not be so reduced because of reduced lubrication effect. Conversely, in case that the amount is too much, the grease would flow out of the sliding surfaces thereby to stick to the other area where lubricating agent is not required.